Prescribing patterns of methylphenidate and atomoxetine containing products in a section of the private health care sector of South Africa

Abstract

The general aim of this study was to investigate the prescribing patterns of products that contain methylphenidate or atomoxetine in a section of the private health care sector of South Africa. A quantitative, retrospective drug uitilisation review was performed according to data obtained from the database of a South African medicine claims pharmacy benefit management company's for three consecutive study years (Le. 2005 to 2007). The results indicated that a total of 7,990 patients had been prescribed products that contained methylphenidate or atomoxetine in 2005. The total for 2006 was 8,575 and it decreased to a total of 7,828 in 2007. Of all the patients who received the mentioned products, the percentage for females increased from 27.75% (N = 7,990) in 2005 to 29.06% (N =7,828) in 2007. With regard to the same products the percentage for males decreased from 72.03% (N = 7,990) in 2005 to 70.89% (N = 7,828) in 2007. The ratio for the gender-related prescribing patterns of medicine items that contained methylphenidate or atomoxetine in this section of the private health care sector of South Africa was ± 2.55:1 for males to females in comparison with the international male:female ratio of 3:1. According to the medicine claims on the database for 2005 the total number of prescriptions that indicated products containing methylphenidate or atomoxetine was calculated as 8,522, 798 (i.e. N = 8, 522,798) or as a percentage of 0.32% prescriptions. The percentage showed an increase to 0.41 % in 2007 (N = 8,015,538). Of all the medicine items containing methylphenidate or atomoxetine those products that contained atomoxetine represented 4.69% and those that contained methylphenidate represented 95.31%. In 2005 the average cost per prescription that indicated items containing methylphenidate or atomoxetine amounted to R318.29 ± R162.09. In 2007 the amount increased to R358.91 ± R208.10. The percentage of children younger than five years of age, and who had been prescribed products containing methylphenidate or atomoxetine, increased from 0.91 % in 2005 (N = 7,990) to 1.11 % in 2007 (N =7,828). The percentage for children aged 5 to 12 years decreased from 53.62% in 2005 to 49.23% in 2007. For adolescents the percentage increased from 26.32% in 2005 to 27.35% in 2007. The same pattern repeated itself in the case of adults (age 18+ years). Among the top trade name products prescribed were Ritalin LA 20mg®, Ritalin 20mg®, Concerta 36mg®, Ritalin LA 30mg® and Concerta 18mg®. Possible drug-drug interactions were found between products containing methylphenidate or atomoxetine and products containing imipramine, amitriptyline and carbamazepine. Findings indicated that the number of products containing methylphenidate or atomoxetine increased from 2005 to 2007, while also revealing that those products containing methylphenidate remained in the majority. The average costs of products containing methylphenidate or atomoxetine increased from 2005 to 2007.